A silver halide color photographic material generally includes silver halide emulsion layers light-sensitive to the wavelengths corresponding to the three primary colors, that is, blue, green and red respectively, and capable of producing yellow, magenta and cyan hues respectively to form a colored image by the so-called subtractive process. The reproduced colored image will, therefore, depend greatly on the color sensitivity of each layer and the spectral absorption characteristics of the colors developed in the layers.
Generally, these characteristics have not always been their theoretical best due to restrictions such as the color developabilities of compounds used. Various improvements, however, have been made as to the color reproducibility of magenta couplers since the hue of the developed color of magenta couplers is important in view of the color reproducibility. Particularly, pyrazoloazole type magenta couplers are excellent in spectral absorption characteristics of the hue of the developed color.
For example, to improve the hue of the developed color of magenta couplers, anilino-type magenta couplers (see Japanese Patent Application (OPI) Nos. 74027/74, 111631/74, etc.) (the term "OPI" as used herein refers to a "published unexamined Japanese patent application) that are considered 5-pyrazolone-types and show better results with respect to spectral absorption characteristics than when ureido-type magenta couplers and acylamino-type magenta couplers are developed. Further, pyrazolotriazole-type magenta couplers, as described in U.S. Pat. No. 3,725,067, that are low in undesirable subabsorption are also developed. Couplers of this type are low in undesirable absorption in the blue light wavelength region and the red light wavelength region, are advantageous in color reproducibility, are stable to light, heatt and humidity and upon color development result in excellentt obtained images which are less yellowed. This phenomenon is probably due to the fact that the couplers themselves negligibly decompose, in comparison to the dye images obtained when 5-pyrazolone-type magenta couplers are used. On the other hand, the pyrazoloazole type magenta couplers are disadvantageous in comparison to the 5-pyrazolone type magenta couplers in that when the photosensitive materials are stored for a long period of time before their use, the sensitivity is undesirably lowered and fogging of the emulsion would result.
Known methods of preventing undesirable changes in photographic performance observed during the storage or developing treatment from occurring, particularly of preventing fog from occurring, include the addition into photosensitive materials or treating liquids, heterocyclic compounds such as 1-phenyl-5-mercaptotetrazole as disclosed in Belgian Patent 671,402, U.S. Pat. Nos. 3,295,976, 3,376,310, 3,615,616, 3,071,465, 3,420,664 and 2,403,927, Japanese Patent Application (OPI) Nos. 37436/75 and 95728/83, etc., benzotriazoles as disclosed in British Patents 919,061 and 768,438, U.S. Pat. Nos. 3,157,509 and 3,082,088, German Patent 617,712, etc., benzimidazoles as disclosed in U.S. Pat. Nos. 3,137,578, 3,148,066 and 3,511,663, British Patents 271,475, 1,344,548, 3,148,066 and 3,511,663, German Patents 708,424, 635,769 and 2,205,539, etc. and imidazoles as disclosed in U.S. Pat. Nos. 3,106,467, 3,420,670, 1,763,990, 2,271,229, etc.
However, if only these compounds are used, the effect of preventing formation of fog during the storage of pyrazoloazole couplers from increasing is not sufficient, or even if this effect is sufficient, the sensitivity is lowered or other disadvantages are observed. Although other various compounds have been studied, compounds that can satisfactorily prevent the formation of fog from increasing during storage without lowering the sensitivity have not been found hitherto.
Although the present inventors have suggested using benzothiazole compounds in Japanese Patent Application (OPI) No. 94918/75 and tetrazole compounds in Japanese Patent Application (OPI) No. 95728/83, the effect of these compounds for preventing fog from increasing, particularly after storage, without at the same time lowering the sensitivity is insufficient.